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astNorm
-
Normalise a set of Frame coordinates
- Description:
- This function normalises a set of Frame coordinate values which
might be unsuitable for display (e.g. may lie outside the
expected range) into a set of acceptable values suitable for
display.
- Synopsis:
- void astNorm( AstFrame
this, double value[] )
- Parameters:
-
this
-
Pointer to the Frame.
-
value
-
An array of double, with one element for each Frame axis
(Naxes attribute). Initially, this should contain a set of
coordinate values representing a point in the space which the
Frame describes. If these values lie outside the expected
range for the Frame, they will be replaced with more
acceptable (normalised) values. Otherwise, they will be
returned unchanged.
- Notes:
- For some classes of Frame, whose coordinate values are not
constrained, this function will never modify the values
supplied. However, for Frames whose axes represent cyclic
quantities (such as angles or positions on the sky), coordinates
will typically be wrapped into an appropriate standard range,
such as zero to 2
pi.
- The NormMap class is a Mapping which can be used to normalise a
set of points using the
astNorm function
of a specified Frame.
- It is intended to be possible to put any set of coordinates
into a form suitable for display by using this function to
normalise them, followed by appropriate formatting
(using astFormat).
Next: astNormMap - Create a NormMap
Up: AST Function Descriptions
Previous: astNegate - Negate the area represented by a Region
AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk
Copyright (C) 2009 Science \& Technology Facilities Council